Gunsmithing Parkerizing a M40

[para1505]

I do not anything about coatings. I am going to do a M40 build. On the build thread it states that the barrel and receiver a parkerized green. Why do they not look green? They look matt black. I asked this question on the build thread but no one has responded.

 

[bptactical]

There are two basic parkerizing processes, zinc phosphate and manganese phosphate. Zinc phosphating (rarely used now)will yield a larger grain, grey hue where the manganese phosphate will yield a finer grained dark charcoal to black color. The greenish hue seen on older firearms is typically zinc phosphate that has been exposed to cosmoline/oils for long periods.
You can get dyes that are a pre or post treatment to the parkerizing that will lend a greenish tint to manganese phosphating. There are also a variety of homespun witches brews folks use to get the tint.